Technical session talks from ICRA 2012

TechTalks from event: Technical session talks from ICRA 2012

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Biologically Inspired Robotics

In the context of underwater robotics, positioning and coordination of mobile agents can prove a challenging problem. To address this issue, we propose the use of electric sensing, with a technique inspired by weakly electric fishes. In particular, the approach relies on one or several of the agents applying an electric field to their environment. Using electric measures, others agents are able to reconstruct their relative position with respect to the emitter, over a range that is function of the geometry of the emitting agent and of the power applied to the environment. Efficacy of the technique is illustrated using a number of numerical examples. The approach is shown to allow coordination of unmanned underwater vehicles, including that of bio-inspired swimming robotic platforms.

Electric fish feel the perturbations of a selfgenerated electric field through their electro-receptive skin. This sense allows them to navigate and reconstruct their environment in conditions where vision and sonar cannot work. In this article, we use a sensor bio-inspired from this active sense to address the problem of small objects reconstruction and electrolocation. Based on a Kalman filter, any small object in the surrounding of the motion controlled sensor can be encapsulated into an equivalent sphere whose location is well estimated by the filter. Experimental results illustrate the feasibility of the approach.

Building autonomous underwater robots is a challenging problem. Different sensory modalities have been employed successfully, some inspired by human and animal senses. The European ANGELS project uses an electric sense inspired by weakly electric fish. These fish have the unique ability to navigate and orient in complete darkness by using self-produced electrical fields. They emit electric signals into the environment, which in turn they perceive with an array of electroreceptor organs in their skin. The fish's whole body serves as an antenna, which shapes the emitted electrical field. As a result, the animals are able to detect, localize and analyze objects in their vicinity and to perceive a 3-dimensional electrical picture of their surroundings. Here, we review biological experimental results highlighting the animal's perceptual abilities, which allow them to navigate in extreme environments where vision can not be used. In addition, electric fishes use electric signals for communication. Behavioral communication strategies such as synchronization of electric signals and fixed-order-signaling can play a role in group coherence. Because of their unique sensory abilities, electric fish can serve as a model system for roboticists building underwater vehicles that can communicate and navigate in extreme environments where vision is not possible. In ANGELS, the electric sense is used to navigate a robot without knowledge of the surroundings, keep multi robots in formation, reco

Morphology, perception and locomotion are three key features highly inter-dependent in robotics. This paper gives an overview of an underwater modular robotic platform equipped with a bio-inspired electric sense. The platform is reconfigurable in the sense that it can split into independent rigid modules and vice-versa. Composed of 9 modules, the longer entity can swim like an eel over long distances, while once detached, each of its modules is efficient for small displacements with a high accuracy. Challenges are to mechanically ensure the morphology changes and to do it automatically. Electric sense is used to guide the modules during docking phases and to navigate in unknown scenes. Several aspects of the design of the robot are described and a particular attention is paid to the inter-module docking system. The feasibility of the design is assessed through experiments.

This article proposes a solution to the problem of the navigation of underwater robots in confined unstructured environments wetted by turbid waters. The solution is based on a new sensor bio-inspired from electric fish. Exploiting the morphology of the sensor as well as taking inspiration from passive electro-location in real fish, the solution turns out to be a sensory-motor loop encoding a simple behavior relevant to exploration missions. This behavior consists in seeking conductive objects while avoiding insulating ones. The solution is illustrated on experiments. It is robust and works even in very unstructured scenes. It does not require any model and is quite cheap to implement

Thanks to an electro-sensible skin, some species of fish can feel the perturbations of a self generated electric field caused by their surroundings variations. Known under the name of &quot;electric-sense&quot;, this ability allows these fish to communicate and navigate in confined surroundings wetted by turbid waters where vision and sonar cannot work. Based on a bio-inspired electric sensor recently proposed in [1], this article presents a first attempt to use electric sense for the navigation in formation of a set of rigid underwater vehicles. The navigation strategy combines some behaviors observed in electric fish as well as a follower-leader strategy well known from multi-robot navigation. Being based one the servoing of the electric measurements, these laws do not require the knowledge of the location of the agents as this is usually the case in multi-robot navigation. At the end of the analysis, sufficient convergence conditions of the resulting control laws are given. Moreover, some limits on the possible motion of the leader are exhibited and the importance of the choice of controlled outputs is discussed too. Finally, simulation results illustrate the feasibility of the approach.